Question

When a weak acid is titrated with a strong base, the pH at the equivalence point is ___. Select one:

a. equal to the base pKb.
b. equal to 7
c. less than 7.
d. greater than 7.
e. equal to the acid pKa.

Answer 1

The pH at the equivalence point for the titration of a weak acid with a strong base is greater than 7 due to the presence of a basic conjugate base in the solution.

Step-by-step explanation:

When a weak acid is titrated with a strong base, the pH at the equivalence point is greater than 7. This is because the conjugate base formed from the weak acid reacting with the strong base is able to accept hydrogen ions (H+), thereby creating a solution that is more basic than neutral water (pH of 7).

At the equivalence point, the amount of acid equals the amount of base added, and you typically have the conjugate base of the weak acid in solution, which affects the resulting pH. For accurate titration results, an indicator such as phenolphthalein with a pKin > 7.0 should be used when titrating a weak acid with a strong base.